Tropoelastin (TE), the soluble precursor of insoluble elastin fibers, is produced in minimal amounts in adults. Burn injuries result in inflexible collagen-rich scars because of lack of elastin fiber formation. We studied the feasibility of using recombinant human tropoelastin to enable elastin fiber production in burn and surgical scars to improve skin flexibility. In a swine hypertrophic burn scar model, normal skin and 3 × 3-cm partial thickness thermal burns underwent dermatome resection at 1 week post burn and randomized to four subcutaneous injections of saline or TE (either 0.5, 5, or 10 mg/ml) spaced 3 days apart. Two burn sites received TE injections after wound closure (0.5 or 10 mg/ml). At 90 days, skin hardness, flexibility, and histology were evaluated. All injury sites developed hypertrophic scars. New elastin fibers were found in burn scars in all injuries injected after skin closure with low (5/5) and high (6/6) TE doses (P < .05). No elastin fibers were observed without TE treatment. No significant differences in skin hardness, flexibility, or inflammation were observed. This is the first report demonstrating that subcutaneous injections of TE into surgical and burn injuries can safely produce new elastin fibers in scars. Despite the development of new elastin fibers, skin flexibility was not improved, possibly because of insufficient elastin fiber maturation or the hypertrophic model used. The ability to restore elastin fiber formation in adult skin after burns, trauma, and surgery may improve skin regeneration and reduce disabling complications of scar formation.

This study examined the long-term safety and effectiveness of a chitosan hemostatic dressing (CHD) in a porcine laparoscopic partial nephrectomy (LPN) model. Eighteen miniswine underwent treatment of using CHD or Surgicel(®) and Tisseel(®) (S/T) for renal parenchymal hemostasis after LPN. The animals were followed up for 6 and 12 months. Surgical procedure related complications, hematological and blood chemical changes were monitored. Histopathological examination was performed on the treated and untreated tissue and organs. All animals had initial hemostasis and survived without any immediate or delayed complications in both CHD and S/T groups. The animals with CHD treatment left large amounts of chitosan residuals on the resected kidney that associated with greater inflammatory scores when compared to the S/T treated animals. This long-term study showed that CHD residuals remained for 12 months and resulted in local inflammation in the LPN model. Despite lack of signs and symptoms of clinical significance in the animals, a further investigation should be conducted to understand the risk of slow degradation of CHD.

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The stability of PF is affected by the pore characteristics of the filter used for foam generation and enhanced by the presence of a small amount of BZK. The improved foam, if shown to be efficacious in animal models of contraception, could lead to a safe, simple and inexpensive method alternative to surgical contraception.